Semiconductor processing apparatus comprising a coating formed from a solid solution of yttrium oxide and zirconium oxide

ABSTRACT

A ceramic article useful in semiconductor processing, which is resistant to erosion by halogen-containing plasmas. The ceramic article is formed from a combination of yttrium oxide and zirconium oxide. In a first embodiment, the ceramic article includes ceramic which is formed from yttrium oxide at a molar concentration ranging from about 90 mole % to about 70 mole %, and zirconium oxide at a molar concentration ranging from about 10 mole % to about 30 mole %. In a second embodiment, the ceramic article includes ceramic which is formed from zirconium oxide at a molar concentration ranging from about 96 mole % to about 94 mole %, and yttrium oxide at a molar concentration ranging from about 4 mole % to about 6 mole %.

This application is a divisional application of U.S. application Ser.No. 12/660,068, filed on Feb. 19, 2010, and entitled: “SemiconductorProcessing Apparatus Which Is Formed From Yttrium Oxide and ZirconiumOxide To Produce A Solid Solution Ceramic Apparatus”, which is currentlypending; which is a continuation application of U.S. application Ser.No. 11/796,210, filed Apr. 27, 2007, and entitled: “Method Of ReducingThe Erosion Rate Of Semiconductor Processing Apparatus Exposed ToHalogen-Containing Plasmas, which has gone abandoned.

The present application is related to a series of applications filed byvarious inventors of the present application, many of the applicationsrelate to the use of a yttrium-oxide comprising ceramic in the form of acoating, to provide a plasma-resistant surface which is useful insemiconductor processing applications. The applications include U.S.application Ser. No. 10/075,967 of Sun et al., filed Feb. 14, 2002,titled: “Yttrium Oxide Based Surface Coating For Semiconductor ICProcessing Vacuum Chambers”, which issued as U.S. Pat. No. 6,776,873 onAug. 17, 2004; U.S. application Ser. No. 10/898,113 of Sun et al., filedJul. 22, 2004, titled: “Clean Dense Yttrium Oxide Coating ProtectingSemiconductor Apparatus”, which is currently pending; and U.S.application Ser. No. 10/918,232 of Sun et al., filed Aug. 13, 2004,titled: “Gas Distribution Plate Fabricated From A Solid YttriumOxide-Comprising Substrate”, which is currently pending. Additionalrelated applications filed, which are a divisional and a continuationapplication of above-listed applications, include: U.S. application Ser.No. 11/595,484 of Wang et al., filed Nov. 10, 2006, titled: “CleaningMethod Used In Removing Contaminants From The Surface Of An Oxide orFluoride Comprising a Group III Metal”, which is currently pending, andwhich is a divisional application of U.S. application Ser. No.10/898,113; and U.S. application Ser. No. 11/592,905 of Wang et al.,filed Nov. 3, 2006, titled: “Cleaning Method Used In RemovingContaminants From A Solid Yttrium Oxide-Containing Substrate”, which iscurrently pending, and which is a continuation application of U.S.application Ser. No. 10/918,232. The subject matter of all of thesepatents and applications is hereby incorporated by reference.

BACKGROUND

1. Field

The present invention relates to a specialized yttrium oxide comprisingsolid solution ceramic which is highly resistant to plasmas in general,particularly resistant to corrosive plasmas of the kind used in theetching of semiconductor substrates.

2. Description of the Background Art

This section describes background subject matter related to thedisclosed embodiments of the present invention. There is no intention,either express or implied, that the background art discussed in thissection legally constitutes prior art.

Corrosion (including erosion) resistance is a critical property forapparatus components and liners used in semiconductor processingchambers, where corrosive environments are present. Example of corrosiveplasma environments include plasmas used for cleaning of processingapparatus and plasmas used to etch semiconductor substrates. Plasmasused for plasma-enhanced chemical vapor deposition processes often tendto be corrosive as well. This is especially true where high-energyplasma is present and combined with chemical reactivity to act upon thesurface of components present in the environment. The reduced chemicalreactivity of an apparatus component surface or of a liner surface isalso an important property when corrosive gases alone are in contactwith processing apparatus surfaces.

Process chambers and component apparatus present within processingchambers which are used in the fabrication of electronic devices andmicro-electro-mechanical structures (MEMS) are frequently constructedfrom aluminum and aluminum alloys. Surfaces of a process chamber andcomponent apparatus present within the chamber are frequently anodizedto provide a degree of protection from the corrosive environment.However, the integrity of the anodization layer may be deteriorated byimpurities in the aluminum or aluminum alloy, so that corrosion beginsto occur early, shortening the life span of the protective coating.Ceramic coatings of various compositions have been used in place of thealuminum oxide layer mentioned above, and have been used over thesurface of the anodized layer to improve the protection of theunderlying aluminum-based materials. However, current materials used forprotective layers deteriorate over time and eventually leave thealuminum alloy subject to attack by the plasma, even though the lifespan of the protective layer is extended over that of anodized aluminum.

Yttrium oxide is a ceramic material which has shown considerable promisein the protection of aluminum and aluminum alloy surfaces which areexposed to fluorine-containing plasmas of the kind used in thefabrication of semiconductor devices. A yttrium oxide coating has beenused and applied over an anodized surface of a high purity aluminumalloy process chamber surface, or a process component surface, toproduce excellent corrosion protection (e.g. U.S. Pat. No. 6,776,873 toSun et al., mentioned above). In one application, the '873 Patentprovides a processing chamber component resistant to a plasma includingfluorine and oxygen species. The processing chamber component typicallycomprises: a high purity aluminum substrate, where particulates formedfrom mobile impurities present in the aluminum are carefully controlledto have a particular size distribution; an anodized coating on a surfaceof the high purity aluminum substrate; and, a protective coatingcomprising yttrium oxide overlying the anodized coating. The protectivecoating may include aluminum oxide up to about 10% by weight, andtypically comprises 99.95% by weight or greater yttrium oxide. Theprotective coating is typically applied using a method such as spraycoating, chemical vapor deposition, or physical vapor deposition.

U.S. Pat. No. 5,798,016, to Oehrlein et al., issued Aug. 25, 1998,describes the use of aluminum oxide as a coating layer for chamber wallsor as a coating layer for a chamber liner. The Oehrlein et al. referencefurther discloses that since aluminum is reactive with a number ofplasmas, it is recommended that “aluminum oxide or a coating thereof bedisposed on the liner or chamber walls”, because aluminum oxide tends tobe chemically inert. In addition, a protective coating may be appliedover the surfaces of the liner and/or chamber walls. Examples which aregiven include Al₂O₃, Sc₂O₃, or Y₂O₃.

U.S. Patent Application Publication No. US 2001/0003271A1, of Otsuki,published Jun. 14, 2001, and subsequently abandoned, discloses a film ofAl₂O₃, or Al₂O₃ and Y₂O₃, formed on an inner wall surface of the chamberand on those exposed surfaces of the members within the chamber whichrequire a high corrosion resistance and insulating property. An exampleis given of a processing chamber where a base material of the chambermay be a ceramic material (Al₂O₃, SiO₂, AlN, etc.), aluminum, orstainless steel, or other metal or metal alloy, which has a sprayed filmover the base material. The film may be made of a compound of a III-Belement of the periodic table, such as Y₂O₃ The film may substantiallycomprise Al₂O3 and Y₂O_(3.) A sprayed film of yttrium-aluminum-garnet(YAG) is also mentioned. The sprayed film thickness is said to rangefrom 50 μm to 300 μm.

In another application, a ceramic composition of matter comprising aceramic compound (e.g. Al₂O₃) and an oxide of a Group IIIB metal (e.g.Y₂O₃) has been used for a dielectric window of a reactor chamber wheresubstrates are processed in a plasma of a processing gas (e.g. U.S. Pat.No. 6,352,611, to Han et al., issued Mar. 5, 2002). The ceramic compoundmay be selected from silicon carbide, silicon nitride, boron carbide,boron nitride, aluminum nitride, aluminum oxide, and mixtures thereof;however, aluminum oxide is said to be available in a pure form whichdoes not outgas. The Group IIIB metal may be selected from the groupconsisting of scandium, yttrium, the cerium subgroup, and the yttriumsubgroup; however, yttrium is preferred, with the oxide being yttriumoxide. The preferred process for forming or producing the dielectricmember is by thermal processing of a powdered raw mixture comprising theceramic compound, the oxide of a Group IIIB metal, a suitable additiveagent, and a suitable binder agent.

In another application, a protective coating for a semiconductorprocessing apparatus component is described. The protective coatingcomprises aluminum or an aluminum alloy, where the coating includes amaterial selected from, for example, but not limited to:yttrium-aluminum-garnet (YAG); an oxide of an element selected from thegroup consisting of Y, Sc, La, Ce, Eu, and Dy; a fluoride of an elementselected from the group consisting of Y, Sc, La, Ce, Eu, and Dy; andcombinations thereof is used (e.g. U.S. patent application Ser. No.10/898,113 of Sun et al., filed Jul. 22, 2004, and entitled “Clean,Dense Yttrium Oxide Coating Protecting Semiconductor Apparatus”,mentioned above). The coating is applied to a substrate surface bythermal/flame spraying, plasma spraying, sputtering, or chemical vapordeposition (CVD). The coating is placed in compression by applying thecoating at a substrate surface temperature of at least about 150-200° C.

The kinds of protective coatings described above have been used toprotect exposed surfaces of a plasma source gas distribution plate ofthe kind used in semiconductor and MEMS processing apparatus. However,due to the concentration of reactive species which are present at thesurface of the gas distribution plate, the lifetime of the gasdistribution plate has typically been limited, from about 8 processingdays to about 80 processing days, depending on the corrosivity of theplasma created in the processing chamber. To increase the lifetime of acomponent such as a gas distribution plate, a gas distribution plate wasfabricated from a solid yttrium oxide-comprising substrate, as describedin U.S. application Ser. No. 10/918,232 of Sun et al., mentioned above.The solid yttrium oxide-comprising substrate contains up to about 10%aluminum oxide in some instances. The solid yttrium oxide-comprisingsubstrate typically comprises about 99.99% yttrium oxide.

As device geometry continues to shrink, the on-wafer defect requirementsbecome more stringent, as particulate generation from apparatus withinthe processing chamber increases in importance. For plasma dry etchchambers running various halogen, oxygen, and nitrogen chemistries, suchas F, Cl, Br, O, N, and various combinations thereof, for example, theselection of the material used for apparatus components and chamberliners becomes more critical. The materials with good plasma resistanceperformance (which also have adequate mechanical, electrical and thermalproperties), can reduce particle generation, metal contamination, andprovide prolonged component life. This translates to low costs ofmanufacturing, reduced wafer defects, increased lifetime, and increasedmean time between cleaning. Ceramic materials which have been used insuch applications include Al₂O₃, AlN, and SiC. However, the plasmaresistance properties of these ceramic materials is not adequate in manyinstances, particularly when a fluorine plasma source gas is involved.The recent introduction of Y₂O₃ ceramic shows improved plasma resistanceproperties, but this material generally exhibits weak mechanicalproperties that limits its applications for general use in semiconductorprocessing components, processing kits, and chamber liners.

SUMMARY

Semiconductor processing conditions expose semiconductor processingapparatus, such as the interior of processing chambers and the surfacesof components within the processing chambers, to a variety of chemicalreagents and plasma ions which attack processing apparatus surfaces. Theeffect of the attack on an apparatus surface is frequently referred toas erosion of the apparatus surface. It is possible to reduce theerosion rate by selecting a particular material composition for theapparatus surfaces. A protective material may be applied as a coatingover the apparatus surface; however, this may not be the best solutionto avoiding erosion. The coating is constantly getting thinner (eroding)during a plasma etch, and there is an increased risk that the substratebeneath the coating will be attacked by the plasma penetrating thecoating layer. The coating layer may flake off during plasma processingdue to residual stress. While such problems will be significantlyreduced by using a coating of the erosion-resistant materials describedin embodiments herein, in many instances it may be advantageous to forman entire apparatus component from the erosion-resistant materials.However, frequently the materials which are more erosion-resistant aremore crystalline, and an improvement in erosion resistance comes at acost, in the form of decreased mechanical properties (such as ductility)of the apparatus. Ceramic materials which are formed from an oxide of aGroup IIIA, IIIB, IVB and VB element, or combinations thereof, have beendemonstrated to provide erosion resistance to halogen-comprisingplasmas. Embodiments of the present invention pertain to reducing theerosion rate of a ceramic material, typically comprising a Group IIIA,IIIB, IVB, or a Group IVB element, or combinations thereof, whilemaintaining acceptable mechanical properties or improving mechanicalproperties of the component parts made of the ceramic material.

In one embodiment, sintered ceramics are formed which contain a singlesolid solution phase or which are multi-phase, such as two phase andthree phase. The multi-phase ceramics typically contain a yttriumaluminate phase and one or two solid solution phases formed from yttriumoxide, zirconium oxide and/or rare earth oxides. The sintered ceramichas been evaluated under various plasma processing conditions todetermine erosion resistance. The materials which were erosion testedwere also tested for mechanical properties. For example, ceramicmaterials formed from starting compositions in which the Y₂O₃, yttriumoxide, molar concentration ranges from about 50 mole % to about 75 mole%; the ZrO₂, zirconium oxide, molar concentration ranges from about 10mole % to about 30 mole %; and, the Al₂O₃, aluminum oxide, molarconcentration ranges from about 10 mole % to about 30 mole % provideexcellent erosion resistance to halogen-containing plasmas whileproviding advanced mechanical properties which enable handling of solidceramic processing components with less concern about damage to acomponent. In many embodiments, a starting composition for the ceramicmaterials may be one that comprises Y₂O₃ molar concentration ranges fromabout 55 mole % to about 65 mole %, ZrO₂ molar concentration ranges fromabout 15 mole % to about 25 mole %, and Al₂O₃ molar concentration rangesfrom about 10 mole % to about 25 mole %. When the erosion rate is ofgreat concern, the starting material concentration of the ceramicmaterial may be one that comprises Y₂O₃ molar concentration ranges fromabout 55 mole % to about 65 mole %, the ZrO₂ molar concentration rangesfrom about 20 mole % to about 25 mole % and the Al₂O₃ molarconcentration 10 mole % to about 15 mole %. In one embodiment, toproduce a solid apparatus component, these starting materialformulations are compacted into a pelletized form and are sintered usinga method selected from pressureless sintering, hot-press sintering (HP),or hot isostatic press sintering (HIP). These sintering techniques arewell known in the art.

In other embodiments, the starting material compositions listed abovemay be used to form a ceramic coating over the surface of a variety ofmetal and ceramic substrates, including, but not limited to, aluminum,aluminum alloy, stainless steel, alumina, aluminum nitride and quartz,using a technique well known in the art, such as plasma spraying, forexample and not by way of limitation. Typically the aluminum alloy usedis a high purity aluminum alloy of the kind described in U.S. Pat. No.6,766,873 to Sun et al., mentioned above. However, with the improvedmechanical properties which have been obtained, it is recommended thatsolid ceramic apparatus components be used when possible, to avoid theeventual failure of the apparatus to function properly due tointerfacial problems between the coating and the underlying substrate,or to prevent a sudden failure of plasma resistance due to the coatinglayer flaking off, or to prevent plasma penetration of the coating layerthrough defects which may be exposed from within the coating layer asthe coating layer becomes thinner due to erosion.

The addition of zirconium oxide powder to yttrium oxide powder at aconcentration of zirconium oxide, ranging from about 0.1 mole % to about65 mole %, after consolidation by conventional ceramic processing,provides a single solid solution with a cubic yttria crystal structurephase or a cubic fluorite-type crystal structure phase, or provides amixed solid solution of cubic yttria crystal structure phase and cubicfluorite-type crystal structure phase. For the cubic yttria crystalstructure, the cell parameter of the solid solution is smaller than thatof the pure cubic yttrium oxide crystalline structure, due to theformation of yttrium vacancy. For the cubic fluorite-type crystalstructure, the cell parameter of the solid solution is smaller than thatof the pure cubic fluorite-type structure, due to the formation ofoxygen vacancy. The smaller cell parameter improves the plasmaresistance properties of the solid solution of zirconium oxide inyttrium oxide. For example, the erosion rate of a pure solid yttriumoxide ceramic in a CF₄/CHF₃ plasma is about 0.3 μm/hr. The erosion rate(the rate at which a surface is removed in μm (of thickness)/hr) of asolid ceramic of about 69 mole % yttrium oxide and about 31 mole %zirconium oxide is about 0.1 μm/hr, a 3 times slower erosion rate thanpure solid yttrium oxide. This unexpected decrease in erosion rateextends the lifetime of a process chamber liner or an internal apparatuscomponent within the process chamber, so that the replacement frequencyfor such apparatus is reduced, reducing apparatus down time; and, theparticle and metal contamination level generated during a plasma processis reduced, enabling a device fabrication with ever shrinking geometrywith reduced overall cost of the processing apparatus per waferprocessed, on the average. In a first embodiment of this invention, asolid solution-comprising ceramic is formed from yttrium oxide at amolar concentration ranging from about 90 mole % to about 70 mole %, andzirconium oxide at a molar concentration ranging from about 10 mole % toabout 30 mole %, using consolidation by conventional ceramic processing,as mentioned above. In a second embodiment of this invention, a solidsolution-comprising ceramic is formed from yttrium oxide at aconcentration ranging from about 90 mole % to about 80 mole %, andzirconium oxide at a concentration ranging from about 10 mole % to about20 mole %.

While the 0.1 μm/hr erosion rate for the zirconium oxide-containingyttrium oxide solid solution is surprisingly better than that of yttriumoxide at 0.3 μm/hr, and considerably better than of a solid aluminumoxide ceramic at 1.44 μm/hr in the CF₄/CHF₃ plasma, the mechanicalproperties of the zirconium oxide-containing yttrium oxide solidsolution illustrate that an improvement in flexural strength andfracture toughness would be helpful.

A ceramic-comprising semiconductor processing apparatus may be formedfrom a solid solution of zirconium oxide at a molar concentrationranging from about 96 mole % to about 94 mole % and yttrium oxide at amolar concentration ranging from about 4 mole % to about 6 mole %. Theceramic-comprising semiconductor processing apparatus may comprise aceramic coating overlying a high purity aluminum alloy, or theceramic-comprising semiconductor processing apparatus may be a solidbody ceramic. The plasma erosion rate for a solid solution comprisingceramic surface of said semiconductor processing apparatus, when exposedto a halogen-comprising plasma, may range from about 0.1 μm/hr to about0.4 μm/hr. The flexural strength of a solid body ceramic comprising saidsolid solution of zirconium oxide and yttrium oxide may range from about1100 MPa to 1300 MPa.

In one embodiment, the flexural strength and fracture toughness of thezirconium oxide-containing yttrium oxide solid solution are achieved, byadding various amounts of aluminum oxide to the formula for the solidsolution ceramic to form an additional yttrium aluminate phase. Themixture of oxides was pelletized by unidirectional mechanical pressingor cold isostatic pressing of a granular powder formed by spray drying,in combination with a typical content of binders. The green body wasthen pressureless sintered using techniques generally known in the art.The addition of 10 mole % to 30 mole % of alumina significantly improvedthe mechanical properties of the sintered ceramic composition in termsof flexural strength and fracture toughness, as discussed subsequentlyherein. This surprising change in mechanical properties, which indicatesthat fabricated parts could be handled with less risk of fracture, wasachieved with minimal effect on the plasma erosion rate of the ceramicmaterial. For example, the erosion rate of the ceramic containing 69mole % yttrium oxide and 31 mole % zirconium oxide, after exposure to aplasma containing CF₄ and CHF₃, was about 0.1 μm/hr. For the ceramiccontaining about 14 mole % aluminum oxide, the erosion rate afterexposure to the same plasma was also about 0.1 μm/hr. For the ceramiccontaining about 25 mole % aluminum oxide, the erosion rate afterexposure to the same plasma was about 0.2 μm/hr. The relationshipbetween aluminum oxide content, increase in flexural strength, andincrease in erosion rate is not a linear relationship. However, one ofskill in the art can optimize the formula with minimal experimentation,in view of the information provided herein.

As an alternative to adding aluminum oxide to a multi phase metal stablecomposition containing yttrium oxide and zirconium oxide, it is possibleto add HfO₂, hafnium oxide; Sc₂O₃, scandium oxide; Nd₂O₃, neodymiumoxide; Nb₂O₅, niobium oxide; Sm₂O₃, samarium oxide; Yb₂O₃, ytterbiumoxide; Er₂O₃, erbium oxide; Ce₂O₃ (or CeO₂), cerium oxide, orcombinations thereof. In the instance where one of these alternativeoxides is used, the concentration of the oxide in the starting materialformulation ranges from about 0.1 mole % to about 90 mole %, andtypically ranges from about 10 mole % to about 30 mole %.

After mixing of at least one of the alternative oxides listed above withthe Y₂O₃ and ZrO₂ powders used to form a solid solution, the combinationof powders was compacted by unidirectionally mechanical pressing or coldisostatic pressing of the granular powder formed by spray drying with atypical content of binders. The green body was then pressurelesssintered using techniques known in the art. Upon cooling of the sinteredbody, a single phase or two phase solid solution forms, where the solidsolution is a “multi-element-doped” solid solution. One solid solutionexhibits a cubic yttria crystal structure, and another solid solutionexhibits the cubic fluorite-type crystal structure. The solid solutionhas excellent plasma resistance, typically better erosion resistancethan that of the aluminum oxide-comprising solid solutions discussedherein. However, the mechanical properties of theyttria-zirconia-alumina system are somewhat better. All of thesemulti-doped solid solutions exhibit excellent plasma erosion resistanceand improved mechanical properties in comparison with previously knownyttrium oxide-zirconium oxide solid solutions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a photomicrograph of the as-sintered surface of a solidyttrium oxide ceramic at a magnification of 1,000 times.

FIG. 1B shows a photomicrograph of the as-sintered surface of a solidsolution ceramic substrate formed from 63 mole % yttrium oxide, 23 mole% zirconium oxide, and 14 mole % aluminum oxide, at a magnification of1,000 times.

FIG. 1C shows a photomicrograph of the as-sintered surface of a solidsolution ceramic substrate formed from 55 mole % yttrium oxide, 20 mole% zirconium oxide, and 25 mole % aluminum oxide, at a magnification of1,000 times.

FIG. 2A shows a photomicrograph of the surface of a solid yttrium oxideceramic after a test etch using the processing plasmas and timestypically used to etch the various layers of a contact via feature in asemiconductor device. The magnification is 1,000 times.

FIG. 2B shows a photomicrograph of the surface of a solid solutionceramic formed from 63 mole % yttrium oxide, 23 mole % zirconium oxide,and 14 mole % aluminum oxide after a test etch using the processingplasmas and times typically used to etch the various layers of a contactvia feature in a semiconductor device. The magnification is 1,000 times.

FIG. 2C shows a photomicrograph of the surface of a solid solutionceramic formed from 55 mole % yttrium oxide, 20 mole % zirconium oxide,and 25 mole % aluminum oxide after a test etch using the processingplasmas and times typically used to etch the various layers of a contactvia feature in a semiconductor device. The magnification is 1,000 times.

FIG. 3A shows a photomicrograph of the post-etch ceramic of FIG. 2A, butat a magnification of 5,000 times.

FIG. 3B shows a photomicrograph of the post-etch ceramic of FIG. 2B, butat a magnification of 5,000 times.

FIG. 3C shows a photomicrograph of the post-etch ceramic of FIG. 2C, butat a magnification of 5,000 times.

FIG. 4A shows a photomicrograph of the as-sintered surface of a solidsolution ceramic formed from 63 mole % yttrium oxide, 23 mole %zirconium oxide, and 14 mole % aluminum oxide, at a magnification of2,000 times.

FIG. 4B shows a photomicrograph of the surface of the solid solutionceramic shown in FIG. 4A, after exposure of the test coupon to a trenchetch process of the kind described herein. The magnification is 2,000times.

FIG. 4C shows a photomicrograph of the as sintered surface of a solidsolution ceramic formed from 55 mole % yttrium oxide, 20 mole %zirconium oxide, and 25 mole % aluminum oxide, at a magnification of2,000 times.

FIG. 4D shows a photomicrograph of the surface of the solid solutionceramic shown in FIG. 4C, after exposure of the test coupon to a trenchetch process of the kind described herein. The magnification is 2,000times.

FIG. 5A shows a photomicrograph of a solid solution ceramic formedfrom63 mole % yttrium oxide, 23 mole % zirconium oxide, and 14 mole %aluminum oxide after exposure of the test coupon to a metal etch processof the kind described herein. The magnification is 5,000 times.

FIG. 5B shows a photomicrograph of a solid solution ceramic formed from55 mole % yttrium oxide, 20 mole % zirconium oxide, and 25 mole %aluminum oxide after exposure of the test coupon to an etch by aCF₄/CHF₃ plasma. The magnification of 5,000 times.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As a preface to the detailed description, it should be noted that, asused in this specification and the appended claims, the singular forms“a”, “an”, and “the” include plural referents, unless the contextclearly dictates otherwise.

When the word “about” is used herein, this is intended to mean that thenominal value presented is precise within ±10%.

Bulk yttrium oxide has been shown to have very good corrosion resistanceupon exposure to fluorine plasma and other corrosive plasmas which aretypically used in semiconductor manufacturing processes (such as etchprocesses and chemical vapor deposition processes). However, purecrystalline yttrium oxide, while offering very good corrosion resistanceto various etchant plasmas, does not offer good mechanical properties interms of flexural strength and fracture toughness, for example. Toimprove the overall performance and handling capabilities ofsemiconductor component parts and liners, there is a need to improve themechanical properties from those available in pure crystalline yttriumoxide. To obtain the improvement in mechanical properties, it isnecessary to form an alloy of yttrium oxide with a compatible oxide. Theimprovement in mechanical properties needed to be accomplished withoutharming the very good plasma erosion properties of the pure yttriumoxide.

In consideration of the Gibbs Formation Free Energy of various ceramicmaterials which might be compatible with yttrium oxide, we determinedthat it is more difficult to form fluorides than oxides for yttrium andaluminum elements, so that yttrium oxide and aluminum oxide are expectedto provide good resistance to a fluorine-containing plasma. The GibbsFormation Free Energy of zirconium fluoride is similar to that foryttrium fluoride. Further, in a homogeneous amorphous oxyfluoride, or aglass-ceramic composite oxyfluoride, increasing the zirconium fluoridecontent can decrease the free energy of the final oxyfluoride to make itmore stable.

EXAMPLE EMBODIMENTS Example One Etch Plasma Process Conditions forErosion Rate Testing

Tables One-Three, below, provides the etch plasma compositions and etchplasma processing conditions which were used for evaluation of a seriesof test coupon materials. There were three basic different sets of etchplasma conditions which were used for the erosion rate testing: 1)Trench etching, where the etch plasma source gas and etch processconditions were representative of etching a trench feature size beyond65 nm technology, i.e. smaller than 65 nm, into a multilayeredsemiconductor substrate. Such a substrate typically includes anantireflective coating (ARC or BARC) layer, an organic or inorganicdielectric layer, a metal layer, and an etch stop layer. Contact Viaetching, where the etch plasma source gas and etch process conditionswere representative of etching a contact via having an aspect ratio ofabout 30 in production and 40 plus in the developed device substrate,and having a diameter of beyond 65 nm technology into a multilayeredsemiconductor substrate including a buried ARC (BARC) layer, adielectric layer and a stop layer; and 3) Metal etching, here the etchplasma source gas and etch process conditions were representative ofetching an overlying titanium nitride hard mask and an aluminum layer,where the etch plasma source gas and etch process conditions are beyond65 nm technology.

The trench etching process and the contact via etching process werecarried out in the ENABLER™ processing system, and the metal etchingprocess was carried out in the DPS™ processing system, all availablefrom Applied Materials, Inc. of Santa Clara, Calif.

TABLE ONE Process Conditions for Trench Etch Erosion Rate Test TrenchPlasma Subr Etch Source Bias Subr Simulation CF₄ * O₂ * CHF₃ * N₂ * Ar *Power ¹ Pr ² Power ³ Temp ⁴ Time ⁵ Etch Step 150 30 300 1,000 40 35 OneEtch Step 400 1200 220 400 40 40 Two Etch Step 175 15 1500 150 500 40 39Three Etch Step 500 100 10 200 40 55 Four * All gas flow rates are insccm. ¹ Plasma Source Power in W. ² Pressure in mTorr. ³ Substrate BiasPower in W. ⁴ Substrate Temperature in ° C. ⁵ Time in seconds.

TABLE TWO Process Conditions for Via Etch Erosion Rate Test Via EtchSimulation CF₄ * C₄F₆ * CHF₃ * CH₂F₂ * Ar * O₂ * N₂ * Etch Step 80 80One Etch Step 28 15 20 500 31 Two Etch Step 40 650 30 Three Etch Step200 Four Etch Step 500 Five Plasma Substrate Via Etch Source BiasSubstrate Simulation Power ¹ Pr ² Power ³ Temp ⁴ Time ⁵ Etch Step 80 40040 50 One Etch Step 400 30 1700 40 60 Two Etch Step 30 1700 40 60 ThreeEtch Step 1000 50 100 40 45 Four * All gas flow rates are in sccm. ¹Plasma Source Power in W. ² Pressure in mTorr. ³ Substrate Bias Power inW. ⁴ Substrate Temperature in ° C. ⁵ Time in seconds.

TABLE THREE Process Conditions for Metal Etch Erosion Rate Test MetalPlasma Subr Etch Source Bias Prc Subr Simul. Cl₂ * BCl₃ * C₂H₄ * Ar *CHF₃ * N₂ * Power ¹ Power ² Pr ³ Temp ⁴ Time ⁵ Etch 60 3 20 1000 100 840 30 Step One Etch 25 40 10 5 500 150 10 40 18 Step Two Etch 60 40 20700 120 18 40 30 Step Three Etch 60 40 3 1000 200 8 40 23 Step Four Etch30 60 5 50 5 800 170 6 40 15 Step Five * All gas flow rates are in sccm.¹ Plasma Source Power in W. ² Substrate Bias Power in W. ³ Pressure inmTorr. ⁴ Substrate Temperature in ° C. ⁵ Time in seconds.

Example Two Comparative Relative Erosion Rates of Various CeramicMaterials Compared with Aluminum Oxide

Aluminum oxide has frequently been used as a protective layer or linerwhen a semiconductor process makes use of an etchant plasma. Usingaluminum oxide as the base comparative material, we determined therelative etch rates, in a Trench Etch (CF₄/CHF₃) environment. Withaluminum oxide having a relative erosion rate of 1, we found that therelative erosion rate of quartz was about 2.2 times that of aluminumoxide. The relative erosion rate of silicon carbide was about 1.6 timesthat of aluminum oxide. The relative erosion rate of zirconia was about0.8 times that of aluminum oxide. The relative erosion rate of pureyttrium oxide was about 0.19 times that of aluminum oxide. The relativeerosion rate of a yttrium oxide, zirconium oxide, aluminum oxide ceramiccomposite, formed from 55 mole % yttrium oxide, 20 mole % zirconiumoxide, and 25 mole % aluminum oxide was about 0.2 times that of aluminumoxide. The relative erosion rate of a yttrium oxide, zirconium oxide,aluminum oxide ceramic composite, formed from 63 mole % yttrium oxide,23 mole % zirconium oxide, and 14 mole % aluminum oxide was about 0.05times that of aluminum oxide.

Example Three Measured Erosion Rates for Trench Etching Process

With reference to the trench etching method described above, the samplesubstrate test coupon erosion rates measured were as follows. Theerosion rate of aluminum oxide was 1.1 μm/hr. The erosion rate of bulkyttrium oxide was 0.3 μm/hr. The erosion rate of a the a yttrium oxide,zirconium oxide, aluminum oxide ceramic composite, formed from 55 mole %yttrium oxide, 20 mole % zirconium oxide, and 25 mole % aluminum oxidewas 0.1 μm/hr. The erosion rate of a yttrium oxide, zirconium oxide,aluminum oxide ceramic composite, formed from 63 mole % yttrium oxide,23 mole % zirconium oxide, and 14 mole % aluminum oxide was 0.07 μm/hr.

Example Four Measured Erosion Rates for Via Etching Process

With reference to the via etching method described above, the samplesubstrate test coupon erosion rates measured were as follows. Theerosion rate of aluminum oxide was not measured. The erosion rate ofbulk yttrium oxide was 0.16 μm/hr. The erosion rate of a the a yttriumoxide, zirconium oxide, aluminum oxide solid solution, formed from 55mole % yttrium oxide, 20 mole % zirconium oxide, and 25 mole % aluminumoxide was 0.21 μm/hr. The erosion rate of a yttrium oxide, zirconiumoxide, aluminum oxide solid solution, formed from 63 mole % yttriumoxide, 23 mole % zirconium oxide, and 14 mole % aluminum oxide was 0.22μm/hr.

Example Five Measured Erosion Rates for Metal Etching Process

With reference to the metal etching method described above, the samplesubstrate test coupon erosion rates measured were as follows. Theerosion rate of aluminum oxide was 4.10 μm/hr. The erosion rate for bulkyttrium oxide was 0.14 μm/hr. The erosion rate of a the a yttrium oxide,zirconium oxide, aluminum oxide ceramic composite, formed from 55 mole %yttrium oxide, 20 mole % zirconium oxide, and 25 mole % aluminum oxidewas 0.10 μm/hr. The erosion rate of a yttrium oxide, zirconium oxide,aluminum oxide ceramic composite, formed from 63 mole % yttrium oxide,23 mole % zirconium oxide, and 14 mole % aluminum oxide was 0.18 μm/hr.

Example Six Photomicrographs of Yttrium-Oxide-Based Ceramics AfterExposure to a Via Etch Process

FIGS. 1A through 1C show photomicrographs of the surface of a sinteredyttrium-oxide-containing ceramic composite prior to exposure to the viaetch process described herein. The yttrium-oxide-containing ceramiccomposites include: 1) yttrium oxide-zirconium oxide solid solution; and2) yttrium aluminate, when the composition was yttrium oxide 100 partsby weight, zirconium oxide 20 parts by weight, and aluminum oxide 10parts by weight. (This composition is the same as 63 mole % yttriumoxide, 23 mole % zirconium oxide, and 14 mole % aluminum oxide); and 3)yttrium oxide-zirconium oxide-aluminum oxide solid solution, when thecomposition from which the solid solution was formed was yttrium oxide100 parts by weight, zirconium oxide 20 parts by weight, and aluminumoxide 20 parts by weight. (This composition is the same as 55 mole %yttrium oxide, 20 mole % zirconium oxide, and 25 mole % aluminum oxide).All of the photomicrographs are at a magnification of 1,000 times.

FIGS. 2A through 2C show photomicrographs of the sinteredyttrium-oxide-containing ceramic composite subsequent to exposure to thevia etch process described herein. The yttrium-oxide-containing ceramiccomposites include: 1) yttrium oxide-zirconium oxide solid solution; and2) yttrium aluminate, when the composition was yttrium oxide 100 partsby weight, zirconium oxide 20 parts by weight, and aluminum oxide 10parts by weight (This composition is the same as 63 mole % yttriumoxide, 23 mole % zirconium oxide, and 14 mole % aluminum oxide); or whenthe composition was yttrium oxide 100 parts by weight, zirconium oxide20 parts by weight, and aluminum oxide 20 parts by weight (Thiscomposition is the same as 55 mole % yttrium oxide, 20 mole % zirconiumoxide, and 25 mole % aluminum oxide). All of the photomicrographs are ata magnification of 1,000 times.

The surface roughness of the bulk yttrium oxide shown in FIG. 2A hasincreased in roughness substantially. However, the overall surfaceroughness appears to be less than that of the zirconium oxide andaluminum oxide containing sample coupons. The surface roughness of thesolid solution shown in FIG. 2B, which contains 10 parts by weightaluminum oxide appears to have hills and valleys which are flatter thanthe hills and valleys of the solid solution shown in FIG. 2C, whichcontains the 20 parts by weight of aluminum oxide. However, the hillsand valleys on the 10 parts by weight aluminum oxide sample coupon shownin FIG. 2B have more pitting on the surface than in the 20 parts byweight sample coupon shown in FIG. 2C.

FIGS. 3A through 3C show photomicrographs which correspond with FIGS. 2Athrough 2C, respectively, but are at a magnification of 5,000 times.Looking at the surface of the bulk yttrium oxide sample coupon shown inFIG. 3A, the surface is relatively smooth but does show some evidence ofsmall pits. The FIG. 3B solid solution formed from yttrium oxide 100parts by weight, zirconium oxide 20 parts by weight, and aluminum oxide10 parts by weight also shows some small scale pitting present on therougher surface shown in FIG. 2B. The FIG. 3C solid solution formed fromyttrium oxide 100 parts by weight, zirconium oxide 20 parts by weight,and aluminum oxide 20 parts by weigh shows negligible small scalepitting.

Looking at the erosion rates for the three test coupons, it appears thatthe 1,000 times magnification for the post-etch coupons shows bettersurface characteristics related to the erosion rates of the coupons. Theerosion rates were 0.16 μm/hr for the solid yttrium oxide shown in FIG.2A; 0.22 μm/hr for the solid solution of yttrium oxide-zirconiumoxide-aluminum oxide which contained 10 parts by weight aluminum oxide;and 0.21 μm/hr for the solid solution of yttrium oxide-zirconiumoxide-aluminum oxide which contained 20 parts by weight aluminum oxide.

Example Seven Photomicrographs of Yttrium-Oxide-Containing SubstratesAfter Exposure to a Trench Etch Process

FIG. 4A shows a photomicrograph of the as-sintered surface of a solidsolution ceramic composite containing 100 parts by weight yttrium oxide,20 parts by weight aluminum oxide, and 10 parts by weight aluminum oxide(63 mole % yttrium oxide, 23 mole % zirconium oxide, and 14 mole %aluminum oxide), at a magnification of 2,000 times. FIG. 4B shows aphotomicrograph of the surface of the solid ceramic composite of FIG. 4Aafter etching by a trench etch process of the kind shown herein. Bothphotomicrographs are at a magnification of 2,000. The post-etchedsurface appears to be flat and relatively homogeneous. This combinationof photographs suggests that after fabrication of an apparatus such as achamber liner or a component part, it may be advisable to “season” thepart by exposing it to an exemplary plasma etch process prior tointroducing the apparatus into a semiconductor device productionprocess. The erosion rate for the solid solution ceramic compositecontaining the 10 parts by weight of aluminum oxide, after exposure tothe trench etch process, was about 0.08 μm/hr.

FIG. 4C shows a photomicrograph of the as-sintered surface of a solidsolution ceramic composite containing 100 parts by weight yttrium oxide,20 parts by weight aluminum oxide, and 20 parts by weight aluminum oxide(55 mole % yttrium oxide, 20 mole % zirconium oxide, and 25 mole %aluminum oxide). FIG. 4D shows a photomicrograph of the surface of thesolid solution ceramic composite of FIG. 4C after etching by a trenchetch process of the kind shown herein. Both photomicrographs are at amagnification of 2,000. The post-etched surface appears to be flat andrelatively homogeneous. This combination of photographs suggests thesame seasoning process described above for newly fabricated apparatus.The erosion rate of the solid solution ceramic composite containing the20 parts by weight of aluminum oxide, after exposure to the trench etchprocess, was about 0.07 μm/hr.

Example Eight Photomicrographs of Yttrium-Oxide-Containing CeramicComposites After Exposure to a Metal Etch Process

FIG. 5A shows a photomicrograph of a two phase solid solution ceramiccomposite formed from 100 parts by weight of yttrium oxide, 20 parts byweight of zirconium oxide and 10 parts by weight of aluminum oxide (63mole % yttrium oxide, 23 mole % zirconium oxide, and 14 mole % aluminumoxide) after exposure of the test coupon to a metal etch process of thekind described herein. The magnification is 5,000 times. FIG. 5B shows aphotomicrograph of a two phase solid solution ceramic composite formedfrom 100 parts by weight of yttrium oxide, 20 parts by weight ofzirconium oxide, and 10 parts by weight of aluminum oxide (55 mole %yttrium oxide, 20 mole % zirconium oxide, and 25 mole % aluminum oxide)after exposure of the test coupon to a metal etch process of the kinddescribed herein. The magnification is 5,000 times. A comparison ofthese two photomicrographs shows that the two phase solid solutioncontaining the higher content of aluminum oxide has an increased amountof the darker phase, which is yttrium aluminate. The erosion rate of thetwo phase solid solution ceramic composites containing the 10 parts byweight of aluminum oxide, after exposure to the trench etch process, wasabout 0.18 μm/hr, while the erosion rate of the two phase solid solutionceramic composite containing the 20 parts by weight of aluminum oxide,after exposure to the trench process was about 0.10 μm/hr.

Example Nine Relative Physical and Mechanical Properties ofYttrium-Oxide-Containing Substrates

Table Four below shows comparative physical and mechanical propertiesfor the bulk, pure yttrium oxide ceramic and for various yttrium-oxidecontaining solid solution ceramics.

TABLE FOUR 100 Y₂O₃ 100 Y₂O₃ 100 ZrO2 100 Y₂O3 20 ZrO₂ 20 ZrO2 Material3 Y₂O₃ 20 ZrO₂ 10 Al₂O₃ 20 Al₂O₃ Starting parts by parts by parts byparts by Composition Y₂O₃ Al₂O₃ weight weight. weight weight Flexural100-150 400 1200 ± 100 137 215 172 Strength (MPa) Vickers 5.7 17.2 11.99.3 9.4 9.6 Hardness (5 Kgf)(GPa) Young's 140-170 380 373 190 190 202Modulus (GPa) Fracture 1.0-1.3 3.5 10.9 1.3 1.6 1.7 Toughness (Mpa ·m^(1/2)) Thermal 13.7  33 2.9 4.7 3.5 Conductivity (W/m/° K) Thermal130-200 200 130-200 150-200 Shock Resistance (ΔT) ° C. Thermal 7.2 7.79.4 9.0 8.5 Expansion × 10⁻⁶/K (20-900° C.) Dielectric 12.3-13   9.9 —15.0 15.5 Constant (20° C. 13.56 MHZ) Dielectric Loss <20    0.5 — <20<20 — Tangent × 10⁻⁴ (20° C. 13.56 MHZ) Volume 10¹²-10¹³ 10¹⁵ — 10¹¹10¹⁶-10²² — Resistivity at RT (Ω · cm) Density  4.92 3.95 5.89 5.19 4.904.86 (g/cm³) Mean Grain 10-25 — 0.5-1.0 5-10 3-6 3-6 Size (μm) PhaseY₂O₃ Al₂O₂ Zr_(1−x)Y_(x)O₂ F/C—Y₂O₃ F/C—Y₂O₃ F/C—Y₂O₃ Composition ss ssss and Y₄Al₂O₉ Y₄Al₂O₉ and YAlO₃ Plasma Erosion 0.3 1.44 0.3 0.1 0.1 0.2Rate (μm/hr) (CF₄/CHF₃) * All of the solid solution ceramic substrateswere sintered using a pressureless sintering technique under a hydrogenprotected atmosphere.

A review of the plasma erosion rate clearly shows the advantages of thesolid solution yttrium oxide, zirconium oxide, aluminum oxide ceramicswhich have been described herein. We have demonstrated that it ispossible to reduce the erosion rate of a ceramic material of this kind,while maintaining acceptable mechanical properties, which enable easierhandling of the apparatus without risk of damage to the apparatus.

Combinations of yttrium oxide, zirconium oxide and aluminum oxide havebeen evaluated, and we have discovered that ceramic materials formedfrom starting compositions in which the Y₂O₃, yttrium oxide, molarconcentration ranges from about 50 mole % to about 75 mole %; the ZrO₂,zirconium oxide, molar concentration ranges from about 10 mole % toabout 30 mole %; and, the Al₂O₃, aluminum oxide, molar concentrationranges from about 10 mole % to about 30 mole %, provide excellenterosion resistance to halogen containing plasmas while providingadvanced mechanical properties which enable handling of solid ceramicprocessing components with less concern about damage to a component. Inmany applications, a starting composition for the ceramic materials maybe one in which Y₂O₃ molar concentration ranges from about 55 mole % toabout 65 mole %, the ZrO₂ molar concentration ranges from about 10 mole% to about 25 mole % and the Al₂O₃ molar concentration ranges from about10 mole % to about 20 mole %. When the erosion rate is of great concern,starting material concentration of the ceramic material may be one inwhich Y₂O₃ molar concentration ranges from about 55 mole % to about 65mole %, the ZrO₂ molar concentration ranges from about 20 mole % toabout 25 mole % and the Al₂O₃ molar concentration 5 mole % to about 10mole %.

Starting material compositions of the kind described above may be usedto form a ceramic coating over the surface of a variety of metal orceramic substrates, including but not limited to aluminum, aluminumalloy, stainless steel, alumina, aluminum nitride, and quartz, using atechnique well known in the art, such as plasma spray, for example andnot by way of limitation. However, with the improved mechanicalproperties which have been obtained, it is recommended that solidceramic apparatus components be used when possible, to prevent suddenfailure of plasma resistance due to coating layer flaking off, ordefects in the coating which appear as the coating thins, or theformation of metal contamination by mobile impurities from theunderlying substrate which migrate into the coating.

The addition of a concentration of zirconium oxide, ranging from about0.1 mole % to about 65 mole % to what was a pure yttrium oxide, providesa solid solution of yttrium oxide and zirconium oxide with the cubicyttria crystal structure or cubic fluorite-type crystal structure, wherethe cell parameter is smaller than that of the pure structure, due tothe formation of yttrium vacancy/oxygen vacancy, respectively. Thesmaller cell parameter of the solid solution crystal structure improvesthe plasma resistance properties of the solid solution of zirconiumoxide in yttrium oxide. For example, the erosion rate of a solid yttriumoxide ceramic in a CF₄/CHF₃ plasma of the kind used to etch a trench ina multilayered semiconductor substrate is about 0.3 μm/hr. The erosionrate of a solid solution ceramic of about 69 mole % yttrium oxide andabout 31 mole % zirconium oxide is about 0.1 μm/hr, a 3 times sloweretch rate than solid yttrium oxide. This unexpected decrease in etchrate extends the lifetime of a process chamber liner or an internalapparatus component within the process chamber, so that: the replacementfrequency for such apparatus is reduced, reducing apparatus down time;the particle amount generated during a process is reduced, improving theproduct properties; the metal contamination generated during a processis reduced, advancing the product properties; and the overall willreduce the overall cost of the processing apparatus per wafer processedwill be reduced, on the average.

While the 0.1 μm/hr erosion rate for the zirconium oxide-containingyttrium oxide solid solution is surprisingly better than that of yttriumoxide at 0.3 μm/hr, and considerably better than of a solid aluminumoxide ceramic at 1.44 μm/hr in the CF₄/CHF₃ plasma, the mechanicalproperties of the zirconium oxide-containing yttrium oxide solidsolution illustrate that an improvement in flexural strength andfracture toughness would be helpful.

In one embodiment, the flexural strength and fracture toughness of thezirconium oxide-containing yttrium oxide solid solution are achieved, byadding various amounts of aluminum oxide to the formula for the solidsolution ceramic to form an additional yttrium aluminate phase. Themixture of oxides was compacted by unidirectional mechanical pressing orcold isostatic pressing of a granular powder formed by spray drying, incombination with a typical content of binders. The green body was thenpressureless sintered using techniques generally known in the art. Theaddition of 10 mole % to 30 mole % of alumina significantly improved themechanical properties of the sintered ceramic composition in terms offlexural strength and fracture toughness. For example, the erosion rateof the ceramic containing 69 mole % yttrium oxide and 31 mole %zirconium oxide, after exposure to a plasma containing CF₄ and CHF₃, wasabout 0.1 μm/hr. For the ceramic containing about 14 mole % aluminumoxide, the erosion rate after exposure to the same plasma was also about0.1 μm/hr. For the ceramic containing about 25 mole % aluminum oxide,the erosion rate after exposure to the same plasma was about 0.2 μm/hr.With respect to the mechanical properties, for example, an overallstarting composition which is about 69 mole % yttrium oxide and about 31mole % zirconium oxide, after sintering exhibits a flexural strength ofabout 137 Mpa, and a fracture toughness of 1.3 Mpa·m^(1/2), as discussedabove. When the overall ceramic composition is about 63 mole % yttriumoxide, about 23 mole % zirconium oxide, and about 14 mole % aluminumoxide, after sintering the flexural strength is about 215 Mpa and thefracture toughness is about 1.6 Mpa·m^(1/2). When the overall ceramiccomposition is about 55 mole % yttrium oxide, about 20 mole % zirconiumoxide, and about 25 mole % aluminum oxide, after sintering the flexuralstrength is about 172 Mpa and the fracture toughness is about 1.7Mpa·m^(1/2). The relationship between aluminum oxide content, increasein flexural strength, and increase in erosion rate is not a linearrelationship. However, one of skill in the art can optimize the formulawith minimal experimentation, in view of the information providedherein.

As an alternative to adding aluminum oxide to a multi phase metal stablecomposition containing yttrium oxide and zirconium oxide is to add HfO₂,hafnium oxide; Sc₂O₃, scandium oxide; Nd₂O₃, neodymium oxide; Nb₂O₅,niobium oxide; Sm₂O₃, samarium oxide; Yb₂O₃, ytterbium oxide; Er₂O₃,erbium oxide; Ce₂O₃ (or CeO₂), cerium oxide, or combinations thereof. Inthe instance where these alternative compounds are used, theconcentration of the alternative compound in the starting materialformulation ranges from about 0.1 mole % to about 90 mole %. Typicallythe concentration used will range from about 10 mole % to about 30 mole%.

After mixing of at least one of the alternative oxides listed above withthe Y₂O₃ and ZrO₂ powders used to form a solid solution, the combinationof powders was compacted by unidirectionally mechanical pressing or coldisostatic pressing of the granular powder formed by spray drying with atypical content of binders. The green body was then pressurelesssintered using techniques known in the art. Upon cooling of the sinteredbody, a single phase or two phase solid solution forms, where the solidsolution is a “multi-element-doped” solid solution. One solid solutionexhibits a cubic yttria crystal structure, and another solid solutionexhibits the cubic fluorite-type crystal structure. The solid solutionhas excellent plasma resistance, typically better erosion resistancethan that of the aluminum oxide-comprising solid solutions discussedherein. However, the mechanical properties of theyttria-zirconia-alumina system are somewhat better. All of thesemulti-doped solid solutions exhibit excellent plasma erosion resistanceand improved mechanical properties in comparison with previously knownyttrium oxide-zirconium oxide solid solutions.

Typical applications for a yttrium oxide-comprising substrate of thekind described herein include, but are not limited to components usedinternal to a plasma processing chamber, such as a lid, lid-liner,nozzle, gas distribution plate or shower head, electrostatic chuckcomponents, shadow frame, substrate holding frame, processing kit, andchamber liner. All of these components are well known in the art tothose who do plasma processing.

The above described exemplary embodiments are not intended to limit thescope of the present invention, as one skilled in the art can, in viewof the present disclosure, expand such embodiments to correspond withthe subject matter of the invention claimed below.

1. An article which is resistant to erosion by halogen-containingplasmas used in semiconductor processing, said article comprising: Asubstrate coated with a solid solution ceramic formed from a combinationof yttrium oxide and zirconium oxide, wherein a molar concentration ofyttrium oxide ranges from about 90 mole % to about 70 mole % and a molarconcentration of zirconium oxide ranges from about 10 mole % to about 30mole %.
 2. A ceramic-coated article in accordance with claim 1, whereinsaid solid solution ceramic is formed from yttrium oxide at aconcentration ranging from about 90 mole % to about 80 mole %, andzirconium oxide at a concentration ranging from about 10 mole % to about20 mole %.
 3. A ceramic-coated article in accordance with claim 1 orclaim 2, wherein a mean grain size of said ceramic ranges from about 2μm to about 8 μm.
 4. A ceramic-coated article in accordance with claim 1or claim 2, wherein a flexural strength of said ceramic coating materialranges from about 120 MPa to about 140 MPa.
 5. A ceramic-coated articlein accordance with claim 1 or claim 2, wherein a fracture toughness ofsaid ceramic coating material ranges from about 1.1 MPa·m^(1/2) to about1.3 MPa·m^(1/2).
 6. A ceramic-coated article in accordance with claim 1or claim 2, wherein said article is selected from the group consistingof a lid, a lid liner, a nozzle, a gas distribution plate, a showerhead, an electrostatic chuck component, a shadow frame, a substrateholding frame, a processing kit, and a chamber liner.
 7. A method ofreducing the plasma erosion of a semiconductor processing apparatusprotected by a solid solution ceramic coating when said apparatus iscontacted by a halogen-containing plasma, while improving mechanicalproperties of said ceramic coating, comprising: forming said solidsolution ceramic coating from yttrium oxide at a molar concentrationranging from about 90 mole % to about 70 mole %, and zirconium oxide ata molar concentration ranging from about 10 mole % to about 30 mole %.8. A method in accordance with claim 7, further comprising forming saidsolid solution ceramic coating from yttrium oxide at a molarconcentration ranging from about 90 mole % to about 80 mole %, andzirconium oxide at a concentration ranging from about 10 mole % to about20 mole %.
 9. A method in accordance with claim 7 or claim 8, whereinsaid plasma erosion rate of said solid solution ceramic coating uponexposure to a halogen-comprising plasma is less than about 0.2 μm/hr.10. A method in accordance with claim 9, wherein said plasma erosionrate of said solid solution ceramic coating upon exposure to ahalogen-comprising plasma ranges from about 0.1 to about 0.2 μm/hr.11.-26. (canceled)
 27. A ceramic-coated article in accordance with claim1 or claim 2, wherein said substrate is selected from the groupconsisting of aluminum, aluminum alloy, stainless steel, alumina,aluminum nitride, and quartz.
 28. A ceramic coated article in accordancewith claim 1 or claim 2, wherein said ceramic coating has a plasmaerosion rate of less than about 0.2 μm/hr.